2009 Honorary Lecturer, Middle East and Africa

The Nile Delta has emerged as a world-class hydrocarbon basin owing to significant gas and condensate discoveries. Early exploration relied on the use of direct hydrocarbon indicators (DHIs) and proved very successful in the shallow Pliocene section. More recently, significant pre-Messinian- (Miocene and Oligocene) aged discoveries have been made, opening these deeper high pressure, high temperature (HPHT) play fairways. However, detailed planning is needed to manage the cost and to mitigate the operational risks of drilling these wells, as well as the successful appraisal and development of the discovered resources.

A major obstacle to exploiting these resources is seismic data quality. In large areas of the offshore Nile Delta, a thin but complex Messinian-aged interval, consisting of anhydrite and interbedded sands and shales, lies immediately above the deep reservoirs. This interval often generates wavefield distortion, attenuation, and the generation of complex multiple diffractions which degrade the underlying seismic image. To overcome this challenge, an innovative acquisition solution was developed and implemented: multi-azimuth seismic (MAZ). Simply put, MAZ is a program in which multiple passes of seismic data are shot over the same subsurface point but at varying azimuths to one another. The resulting data can then be stacked to produce an image with superior noise and imaging characteristics. In addition to the image quality improvements, recent studies have shown that MAZ data may also offer a unique opportunity to further characterize the subsurface by exploiting the multiple independent measures of the overburden and reservoir.

The higher cost of MAZ has been offset by delivering a significant reduction in the risk and expense of deep HPHT drilling operations. MAZ has also proved to be an excellent front-end loading tool to optimize the appraisal and development program and reduce the risk and cost of major projects.